Recording galvanometer



Feb. 15, 1944. c WALLACE 2,341,834

RECORDING GALVANOMETER Original Filed Aug. 18, 1939 IN V EN TOR.

ATTORNEY Patented Feb. 15, 1944 UNlTED STATES PATENT. OFFICE nnconnme GAL'vANoME'rEn Charles F. Wallace, muscles. 1., a'asignor to Wallace & Tier-nan Products, Inc., Belleville, N. 21., a corporation of New Jersey Original application August 18, 1939, Serial No.

290,842. Divided and this application Novcm 'ber 26, 1941, Serial No. 420,459 a 4 Claims. (01. 171495) inexpensive to manufacture; yet quite sensitive and accurate.

Other objects and advantages will appear as the invention is hereinafter disclosed.

Referring to the drawing which illustrates what I now consider to be a preferred physical embodiment of the invention, I have there shown, diagrammatically in some respects, and with parts broken away for clarity in illustration, an

greater magnetic retentlvity, i. e., greater resistance to demagnetization, and are comparatively resistant to corrosion. However, these Alnico" alloys, having the stated desirable properties, are comparatively brittle and practically impossible to work by machining operations other than grinding operations. In my device, the axle III, being offset as shown and above described, does not pass through the rotor or. disc I05, but the latter is imperforate and is suitably secured to the onset portion of the axle III as by soldering the disc I06 to the axle at a point I 26 on the periphery of the disc. Thus while the geometric axis ofoscillation of the disc rotor I06 passes through the disc at its center, the axle III does not actuinstrument embodying the various features of my invention.

The instrument shown comprises a stator I05 which is shown in the form of a spool having a central slot or rotor-receiving opening extending axially of the spool.- A rotonor armature I06 is shownmounted for partial rotation or oscillation; in the stator opening, about a geometric axis which passes through the rotor and is at right angles to the axis of the spool I00 and intersects the last mentioned axis at, or substantially at, a point midway of the ends of the spool.

-The axle I I I, which supports the rotor I06 for oscillation about its geometric axis, is preferably ofl'set as shown'so as to lie outside the spool I05 and yet permit of the desired oscillation of the rotor I06 within its limits of travel. While the axle III maybe supported at one of its ends for rotation or oscillation, it is preferably provided with two ends, on opposite sides of the offset portion of the axle, and each of the axle ends is suitably journaled in a corresponding one v of twebearings presently to be described in greater detail. The opposite end portions of the axle III are co-axial. with the geometric axis of oscillationof the rotor I00.

While the rotor or armature I00 may assume other forms and be made of other materials, it is shown in the shape 'of a circular disc of a magnetic alloy such as that known .as Alnico. These alloys are considerably lighter in weight than other materials, such as cobalt magnet steel, of which such armatures may. be constructed, and-the fAlnico" type of alloys provide ally pass through the disc I06 at all; the disc being, 'as stated, imperforate.

By providing the construction shown, the desired alloy may be employed for the rotor I06;

thereby providing a rotor which is comparatively light in weight, has high magnetic reten-- tivity, and which may be manufactured and assembled with facility and inexpensively.

terial, which is riveted or otherwise suitably secured to' one of the ends of the spool I05;

While the geometric axis about which the rotor I06 oscillates, passes through the stator winding I01, the axle III, being offset as shown and described,'does not pass through the winding I01. Therefore, the construction described has additional advantages with respect to the construction of the deflection-producing winding and the efliciency of operation of the instrument.

If the axle III, instead of being onset, actually passed through the stator, it would be necessary to provide an ofl'set stator winding, or two spaced stator windings, or' otherwise to provide a clearance opening in the winding, for the axle III. By virtue of the construction shown and described, it is possible to employ a single long winding, as shown, having a better space factor, i. e., one producing a greater magnetic flux for a given cross-sectional area, as ther is more wire. and less insulation or other voids-in the construction.

Preferably, the spool I 05 is made'of copper so as to constitute, in eflect, a low resistance short the panel by means of studs I I1, and a rear bearing plate H8 is shown secured to the bars I I0.

The axle III may be made of steel and its opposite ends are preferably conical as shown at H4 and journaled in the small ball bearings H2 I and H3. The bearings H2 and H3 are carried by the front and rear bearing plates H5 and H0, respectively. Either or both of these bearings may be mounted so as to be adjustable in the direction of the geometric axis of the axle Hi and rotor I06. Thus, the front bearing H2 has its race externally threaded to cooperate with internal threads in the bearing plate I I5; a loci; nut H6 being provided to retain the bearing in any desired position to which it has been axially adjusted. The rear bearing H3 may be made similarly adjustable and settable.

In the particular instrument shown, the shaft or axle I I I has secured to one of its end portions a recording arm I22 carryinga marking pen or stylus I25 which traces a record upon the record sheet I02. While the record sheet I02 may be otherwise shaped and otherwise actuated, it is shown in the form of a circular sheet rotated by a suitably timed motor IOI, such as a spring motor or clock-works, mounted on the rear of the panel-I03 and having a drive shaft extending therethrough; the sheet I02 being suitably secured to the said drive shaft at its front vend.

A spiral spring I20 having one of its ends secured to the axle III and its opposite end secured to an arm I2I, in turn secured to the bearing plate H8, may be provided for biasing the rotor I06 and the indicating or recording arm I22. The magnitude of the biasing torque provided by the spring I20 may selectively be varied bysetting the arm I2I, which is angularly adjustable on the bearing plate I I0. I

An arm I24,-secured to the axle III so as to be angularly adjustable thereon, as by means of a set screw, is pmvided with a weight I23 for counter-balancing the arm I22 and the pen or stylus I25. If desired, the arm I24 and its weight I23 may additionally be employed as a substitute for the biasing spring I20, or, supplemental to the spring I20, for providing the desired 'bias ing torque for the rotor I00. To these ends, the weight I23 may be radially adjusted on the arm I24 as by the screw and slot adjustment shown, which, acting in conjunction with the angular adpendent upon the magnitude of the direct current passing through the winding I01.

The instrument shown and described may therefore be employed as a galvanometer or other electrical indicating instrument.-

This application is a division of my co-pending application Serial No. 290,842, filed August 18, 1939, for Methods and systems ofapparatusfor detecting and controlling changes in composition of liquids.

In accordance with the provisions of the patent statutes, I have herein described the principle ofoperation of my invention, together with the apparatus which I now consider to represent the best embodiments thereof, but I desire to have it understood that the apparatus disclosed is only illustrative and that the invention can be carried out by other means. Also, while it is designed to use the various features and elements in the combinations and relations described, some of these may be altered and others omitted, without interfering with the more general results outlined, and the invention extends to such use within the scope of the appended claims.

What I claim is: I

1. An electrical translating device comprising in combination, an imperforate armature of magnetic material, means mounting said armature for angular movement about a geometric axis passing through said armature, and electromagnetic means for angularly deflecting said armature,

said mounting means comprising an axle extending along said axis and having an offset portion secured to an outer edge of said armature to maintain said armature within said electromagnetic means, and means pivotally mounting said axle exteriorly at opposite sides of said electromagnetic means, said armature comprising a separate, permanently magnetized member of high magnetic retentivity secured at an edge thereof to the oilset portion of the axle and magnetically polarized in a direction at an angle to said geometric axis, and said mounting means being adapted to maintain the armature normally in a position with its magnetic flux in angular relationship to that produced. by the elecjustment of the arm I24, providesfor either The disc rotor or armature I06 constitutes a permanent magnet. It is so permanently magnetized as to have a north pole at its periphery and a south pole also on the periphery and diametrically opposite the north pole. By so locating the permanent north and south poles in relation to the winding I01 that the lines of magnetic flux or force parallel the plane of the winding I01, when the latter is deenergized, maxi mum deflecting torque and a substantially uniform deflection of the pen arm I 22 will be attained when the winding I01 is energized. If it is desired to spread the readings at one or the other end of the movement of the arm I22, the permanent magnet I 08 may be so mounted angutromagnetic means.

2. In an electrical translatingdevicain combination, an imperforate disc of magnetic material, mounting means therefor including an axle having an offset portion connected to said disc at its periphery and whose geometric axis of rotation passes through the disc substantially centrally of the latter, and electromagnetic means for 'angularly deflecting said armature, said disc being permanently magnetized with a diametrical polarization and saidmounting means being adapted to maintain thedisc normally in a position with its magnetic flux in angular relationship to that produced by the electromagnetic A means.

larly with respect to the arm I22 as to obtain an 1| 3. An electrical indicating instrument comprising in combination, a deflecting coil, an imperforate armature of magnetic material extending into said coil and substantially surrounded thereby, and mounting means for the armature including an axle wholly outside said coil supporting said armature for oscillation about a geometric axis passing through said coil and through said armature, said axle having an oflset portion extending around said coil and connected to the periphery of said armature, said armature being magnetically polarized in a direction at an angle to said geometric axis, and said mounting means being adapted to maintain the armature normally in a position with its magnetic flux in angular relationship to that fleeting coil.

4. An electrical indicating instrmnent comprising in combination, a-spo'ol of electrically conductivenonmagnetic material, a helical defiecting winding on said spool, an imperforate disc produced by the dearmature of magnetic material extending into the opening in said spool, and means including an axle having an offset portion connected to the periphery 01' said disc for supporting said disc for, angular movement about a geometric axis passing through the center of said disc and through said spool substantially midway of the ends of the latter, said armature consisting of a separate, permanently magnetized disc or high magnetic retentivity, diametrically polarized, and

said supporting means being adapted to maintain: the disc normally in a position with its magnetic flux in angular relationship to that producedby the helical deflecting winding. a V CHARLES F. WALLACE. 

